Osteogenesis imperfecta (OI) is a connective tissue disorder that is caused by an abnormality of type I collagen in over 90% of cases. Due to considerable phenotypic variability, Sillence et al. (1979) developed a classification of OI subtypes: ... Osteogenesis imperfecta (OI) is a connective tissue disorder that is caused by an abnormality of type I collagen in over 90% of cases. Due to considerable phenotypic variability, Sillence et al. (1979) developed a classification of OI subtypes: OI type I with blue sclerae (166200); perinatal lethal OI type II, also known as congenital OI (166210); OI type III, a progressively deforming form with normal sclera (259420); and OI type IV, with normal sclerae. Levin et al. (1978) suggested that OI subtypes could be further divided into types A and B based on the absence or presence of dentinogenesis imperfecta.
On the basis of a study in Australia, Sillence et al. (1979) concluded that in addition to dominantly inherited osteogenesis imperfecta with blue sclerae (OI type I) there is a variety with normal sclerae. This agreed with the ... On the basis of a study in Australia, Sillence et al. (1979) concluded that in addition to dominantly inherited osteogenesis imperfecta with blue sclerae (OI type I) there is a variety with normal sclerae. This agreed with the distinction made by Bauze et al. (1975) and Francis et al. (1975) between 'blue-eyed' and 'white-eyed' OI, and supported by a biochemical difference. Sillence et al. (1979) found only 2 families with the 'white-eyed' type as contrasted with the many 'blue-eyed' families. They suggested that the family reported by Holcomb (1931) fell into the 'blue-eyed' category. Neither blue sclerae nor deafness was noted in the families reported by Ekman (1788) or by Lobstein (1835). Johnson et al. (2002) reported a 35-year-old woman and 2 of her children with what the authors termed a 'variant' of OI type IVB. The woman had shown shortening of the limbs with severe angular malformations of the femora at birth. From 3 months to 1 year, her legs were maintained in plaster casts, which slightly improved the bowing. After starting to walk, her lower limbs showed significant improvement that lasted throughout adulthood. She had pale blue sclerae, which can occur in up to 10% of cases of OI type IV, easy bruising, 3 broken bones in her lifetime, recent development of lumbar spondylolisthesis, and dentinogenesis imperfecta. A son and daughter were shown to be severely affected during gestation. Johnson et al. (2002) noted that the proband had originally been classified as having kyphomelic dysplasia (211350), but molecular analysis showed a mutation in the COL1A2 gene (120160.0050).
In a child with OI type IV, Marini et al. (1989) identified a mutation in the COL1A1 gene (120150.0012). See also de Vries and de Wet (1986) and 120150.0003.
In a patient with OI type IV, ... In a child with OI type IV, Marini et al. (1989) identified a mutation in the COL1A1 gene (120150.0012). See also de Vries and de Wet (1986) and 120150.0003. In a patient with OI type IV, Wenstrup et al. (1988) identified a mutation in the COL1A2 gene (120160.0004), which resulted in increased posttranslational modification along the triple-helical domain.